Communication system



Oct. 23, 1934. D. JOURNEAUX COMMUNICATION SYSTEM Filed Sept. 10, 1952 mm1 R W mm a xk D 04 Patented Oct. 23, 1934 PATENT orFicE 1,977,965COMMUNICATION SYSTEM Didier Journeaux, Wauwatosa, Wis., assignor toAllis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation ofDelaware Application September 10, 1932, Serial No. 632,577

9 Claims.

, This invention relates to communication systems and more particularlyto systems in which the voice or signal level is raised by the use ofamplifying means. a

In communication systems in which a telephone line extends adjacent apower line, disturbing currents may be induced in the telephone linefrom the power line by electrostatic v or by electromagnetic induction.The disturbing 10 action of such currents may be overcome by amplifyingthe voice currents at the transmitting station to an intensity greaterthan that of the disturbing currents, such voice currents then beingreduced to normal level at the receiving station by suitable means whichalso reduce the disturbing currents to a value'suchthat their action nolonger interferes with'the proper understanding of speech. Generally,the amplifier will be energized from the power line so that, when -suchline becomes deenergized for any reason such as the occurrence of adisturbance therein, the amplifier will become inoperative. Under suchconditions, the telephone line will no longer be influenced by the powerline, so that it becomes possible to establish direct connection betweenthe telephone and the power lines without interposition of the theninoperative amplifier thereby permitting normal operation of thecommunication system. Such result is particularly important when thecommunication line is used for controlling the operation of apparatusconnected with the power line or for transmitting verbal orders betweenstations controlling such line. The telephone is automaticallyreconnected by means of a switch responsive to the voltage conditions inthe power line.

It is, therefore, one object of the present invention to provide acommunication system in which signals or voice currents are amplifiedto40 a value higher than that of disturbing currents induced therein.

Another object of the present invention is to provide a communicationsystem in which signals or voice currents are amplified at the sendingstation and reduced at the receiving station.

Another object of the'present invention is to provide a communicationsystem in which signals or voice currents are amplified by means ofamplifiers energized from a supply line inducing 5 interfering currentsin the communication line.

Another object .of the present inventionis to (Cl. 179-78) l interferingcurrents in the communication line.

Another object of the present invention is to provide a communicationsystem comprising a communication line in which signals or voicecurrents are automatically amplified upon energization of a supply lineinducing disturbing currents in the communication line.

Objects and advantages other than those above set forth will be apparentfrom the description when read in connection with the drawing, whichdiagrammatically illustrates one embodiment of the present invention inwhich a plurality of telephone stations are connected by a line andreceive current for power purposes from a come mon supply line.

Referring more particularly to the drawing by characters of reference,reference numeral idesignates a telephone line providing communicationbetween a plurality of telephone stations of which only two areillustrated and aredesignated by A and B. Numeral 2 designates analternating current power line from which power may be obtained at eachtelephone station through transformers 3. When line 2 is energized, itis assumed that such line induces disturbing currents in line 1 due tothe particular construction and to the close proximity of the two lineswhich results in mutual electrostatic or electromagnetic inductiontherebetween. Induction of such currents in line 1 may occur along theentire length of line 2 or only along certain portions thereof, theremaining portions being either remote from line 1 or being soconstructed as to avoid mutual induction therewith. The currents inducedin line 1 by line 2 are assumed to be of such magnitude as to renderspeech transmitted over line 1 difficult to understand or even entirelyunintelligible.

Each station such as A, B comprises a telephone, generally representedby 4 used in connection with an amplifier 6 with which it may beconnected by means of aswitch 7. Each telephone 4 may be of any typeknown in the art, but the component parts thereof must be so connectedas to make such telephone operable in conjunction with the remainingelements of the present system. Each telephone comprises a hand operatedmagneto 8 for the purpose of calling any of the other stations. Magneto8 is connected with one conductor of the line through a switch 11actuated by the switch hook 12 which is actuated by the earpiece orreceiver and is generally in open circuit. When the crank of the magnetois turned, it closes the circuit of the magnet as is well known in theart, to connect such magneto across the two conductors of the line. Apolarized bell 9 is connected across the line through switch 11 forconverting ringing currents into audible signals. A transmitter ormouthpiece 13 is connected in series with a battery 14 and the primarywinding 16 of a transformer or induction coil having a secondary winding17, the circuit being closed through contacts of switch 11. The purposeof transformer 16, 1'7 is to amplify the voice currents to normaltransmission level and to avoid transmission of the direct currentsupplied by battery 14 over the line. A receiver or earpiece 18 may beconnected in series with winding 1'7 or may be connected in series withsecondary winding 19 of a second transformer having its primary winding21 connected across a portion of a resistance 22. Resistance 22 isconnected across the line through switches 11 and '7 and is used as apotentiometer for supplying receiver 18.

Switch '7 comprises a plurality of contacts actuated by a cam 23 whichmay be operated by hand or by means of a solenoid 24 energized fromtransformer 3 through switch 37 and through a hand switch 26. Theposition of switch 7 may thus be controlled by hand or may be controlledin response to the voltage conditions in line 2. Amplifier 6 may be ofany construction known in the art and is shown as comprising a singleamplifying tube 27 connected with the telephone through a condenser 28to prevent the fiow of direct current from tube 2'7 to the line. Theamplifier is energized from a supply transformer 29 supplying arectifying tube 31 connected through suitable filters 32 to apply asubstantially uniform direct current to a voltage divider 33. Thepositive terminal of voltage divider 33 is connected with the plate oftube 27 through a choke coil 30. The input circuit of the amplifier isconnected with the grid of tube 2'7 andwith the negative terminal ofvoltage divider 33, the output circuit being connected with condenser 28and with the negative terminal of voltage divider 33 which constitutes acommon point for both input and output circuits. Transformer 29 isenergized from line 2 through transformer 3 and is connected therewiththrough the contacts 34 of a relay 36, such relay being energized onlywhen line 2 is energized and contacts 37 are closed.

The system is shown so connected that the amplifiers are energized andconnected with the telephones, the telephone receivers being off theirhooks to permit the transmission of speech, such connections being shownto illustrate the functioning of the system. It will easily beunderstood that, when the system is not in operation, the receivers 18are hung on hooks 12 so that switches 11 are reversed and switches 3'?are open, thereby deenergizing relays 36 which open their contacts 34and deenergize amplifiers 6. The system being in the deenergizedcondition described, assuming that it is desired to call station B fromstation A, the operator of station A will operate magneto 8 whichconnects itself across line 1 through switch 11 to send ringing currentsthrough the line. Such currents will thus circulate in station A fromline 1 through magneto 8, switch 11, and back to the line, over the lineto the other stations of the system where they will circulate throughbells 9 and switches 11. Current also circulates in station A throughhell 9 which is connected directly across magneto 8. It will be assumedthat the ringing currents sent over the line were spaced at suchintervals as to constitute a code indicating that communication isdesired with the operator of station B only. Upon completion of the codesignal, the operators in both station A and B lift their receivers 18oiT switch hooks 12 thereby closing switches 3'7. Switches 37 beingclosed, solenoids 24 and relays 36 will be energized thereby bringingswitches '7 into the position shown in the drawing and energizingamplifiers 6 to amplify the voice currents. Assuming first that speechis transmitted from station A to station B, lifting of receiver 18 fromswitch hook 12 reverses switch 11, thereby closing the circuit oftransmitter 13. A current will then flow from battery l l through switch11, winding 16 and transmitter 13, such current being modulated due tothe impulses of speech waves in transmitter 13. By electromagneticinduction, currents are induced in winding 1'7 and will circulate instation A from the negative terminal of voltage divider 33, throughswitch '7, winding 17, switch 7 to the grid of tube 27. The voltageimpressed thereby on grid of tube 2'7 is amplified, and the amplifiedspeech currents will circulate in station A from line 1, through switch11, switch 7,

condenser 28, tube 27, voltage divider 33 back to line 1. Such currentsare then transmitted over line 1 to the other stations, but do not fiowto a material extent through stations other than A and B, in which onlybell 9 is connected to the line, such bell presenting a high impedanceto speech currents. Such voice currents, therefore, largely flow throughstation B, through a circuit from line 1, through resistance 22, switch7, switch 11, back to line 1.

The above circuit also receives disturbing currents induced in line 1from line 2. The voltage across a portion or" resistance 22 is impressedon winding 21 and a voltage is induced in winding 19 so that a currentflows through winding 19 to receiver 18 over switch '7. The voicecurrents transmitted over line 1, having been amplified, must now bereduced to normal level by means of resistance 22 and transformer 19, 21which reduce the interfering currents induced in line 1 by line 2 to alevel such that they no longer interfere with the proper understandingof speech. A portion of the speech current is also received through acircuit of station A similar to the circuit of station B, so that theoperator of station A hears his own voice at normal level and theinterfering noises are reduced to a very low or to an imperceptiblelevel. It will be under stood that if station B calls station A theprocess of operation will be similar but in a reverse direction becausethe two stations are identical in construction.

Assuming that line 2 becomes deenergized upon occurrence of adisturbance therein or for any otherreason, amplifiers 6 will becomedeenergized and will be incapable of transmitting speech currents fromtheir input circuits to their output circuits. Solenoids 24 are alsodeenergized, thereby reversing switches '7 which connect the talkingcircuits of telephones 4 directly to line 1, but do not interfere withthe connections of the ringing circuits. Under such condi tions,assuming that it is again desired to call station B from station A,ringing currents are sent over the line by the same process and over thesame circuits previously described. Upon removal of receivers 18 fromswitch hooks 12, transmitter 13 in station A is again energized frombattery 14 and a current modulated at voice frequency flows throughwinding 16. Voice currents at normal transmission level are then inducedin winding 17 and flow in station A from line 1 over switch 11, switch7, winding 17, two contacts of switch 7, receiver 18, back to line 1.Such currents are transmitted over the line to station B wherein theycirculate in a circuit similar to that described for stationA. The.voice currents are thereby made". audible inreceivers 13 in bothstations. It will ,beunderstood that the transmission of speech will beefiectedin an identical manner from station B back to station A. i x

It may happen that, due to some inherent defect or due to accidentalcauses, one of the amplifiers becomes inoperative, whereupon the stationincluding such amplifier will still be capable of receiving speech, butnot of transmitting speech. To permit two-way. communication even undersuch conditions, the amplifier in both stations may then be disconnectedby reversing cams 23 manually or by deenergizing solenoids 24 by meansof switches 26, thereby reversing switches '7 and connecting telephones4 directly to the line. between the two stations is then possible to theextent permitted by the disturbing action of currents induced from theline 2. 1 r

It may also happen. that only a portion of line 2, connected withvstation E for instance, induces disturbing currents in line 1so-that,'in the event of such portionbeing deenergized, only theamplifier in station A will remain operative, but disturbing currentswill no longer be induced in line 1. The operators in both stations Aand B may then open switches 26 thus obtaining direct connection betweenthe telephones and the line and transmission of speech without use ofamplifiers.

A similar condition prevails if the amplifier in one station, such asstationA, is energized from a source of supply independent of line 2.Upon deenergization of line 2, the operator in station A must then openswitch 26 to reverse switch '7 and connect telephone 4 directly to theline, the telephone in station B having been connected directly to theline because of deenergization of solenoid 24 upon the deenergization ofline 2.

Although but one embodiment of the present invention has beenillustrated and described, it will be apparent to those skilled in theart that various changes and modifications may be made therein withoutdeparting from the spirit of the invention or from the scope of theappended claims.

It is claimed and desired to secure by Letters Patent:

1. In a communication system, a plurality of stations each havingtransmitting and receiving apparatus, an electric line connecting saidstations, a source of electric current, means arranged in each of saidstations for connection with the apparatus in said stations and withsaid source for amplifying the communication currents originating withinsaid stations, and means for automatically connecting and disconnectingthe first said means from the transmitting apparatus within saidstations responsive to the voltage conditions of said source.

2. In a communication system, a plurality of stations each havingtransmitting and receiving apparatus, an electric line connecting saidstations, a source of electric current, means arranged in each of saidstations for connection with the apparatus in said stations and withsaid source for amplifying the communication currents'origi- Two-waycommunication nating within said stations, a switch connected with'eachof said means, a switch controlling the receiving apparatus in each ofsaid stations, said switches cooperating to manually control theconnection of the transmitting apparatus of each ofsaidstationslwithsaid amplifying means associated therewith, andsolenoids severally controlling the connection of each of said meanswith the transmitting apparatus of. each of said stations in response tothe conditions of said source.

3. In a communication system, a power line arrangedladjacent the system,a plurality of stations each having communication transmitting andreceiving apparatus therein, an electrically conductive line connectingsaid stations and subject to interference from said power line, means ineach of said stations and energized from said ofsaid switches andresponsive to energization of said power line to control connection ofthe first said means therewith.

la-In a communication system, a power line arranged adjacent the system,a plurality of stations each'having. communication transmitting andreoeivingapparatus therein, an electrically conductive line connectingsaid stations and subject to interference" from said power line, meansin each of said stations and energized from said power line foramplifying the communication currents originating within said stations,and means responsive to the voltage of said power line to connect thetransmitting apparatus with said connecting line directly when saidpower line is deenergized and through said amplifying means when saidpower line is energized.

5. In a communication system, a power line arranged adjacent the system,a plurality of stations each having transmitting and receiving apparatustherein, an electrically conductive line connecting said stations andsubject to interference from said power line, means in each of saidstations and energized from said power line for amplifying thecommunication currents originating within said stations, means toconnect the transmitting apparatus with said connecting line directlywhen the power line is deenergized and through said amplifying meanswhen said power line is energized, means for connecting said amplifyingmeans with the power line when the power line is energized, and meansresponsive to the voltage of said power line to control operation of thelast two said means.

6. In a communication system, a power line extending adjacent thesystem, a plurality of stations each having transmitting and receivingapparatus therein, an electrically conductive line connecting saidstations and subject to interference from said power line, means in eachof said stations and energized from said power line for amplifying thecommunication currents originating within said stations, meansresponsive to the voltage of said power line to connect the transmittingapparatus in said stations with said connecting line directly when saidpower line is deenergized and through said amplifying means when saidpower line is energized, means for connecting said amplifying means withsaid power line when said power line is energized, and a switchcontrolling the receiving apparatus whereby the last two said means arecontrolled.

7. In a communication system, a power line extending adjacent thesystem, a plurality of stations each having transmitting and receivingapparatus therein, an electrically conductive line connecting saidstations and subject to interference from said power line, means in eachof said stations and energized from said power line for amplifying thecommunication currents originating within said stations, means forreducing the intensity of the amplified communication currents to thenormal level of audibility, and means responsive to the voltage of saidpower line to connect the transmitting and the receiving apparatusdirectly with said station connecting line when the power line isdeenergized and to connect the transmitting apparatus with said stationconnecting line through said amplifying means and to connect thereceiving apparatus with said station connecting line through thesecendsaid means when said power line is energized.

8. In a communication system, a power line extending adjacent thesystem, a plurality of stations each having transmitting and receivingapparatus therein, an electrically conductive line connecting saidstations and subject to interference therefrom, means in each of saidstations and energized from said power line for amplifying thecommunication currents originating within said stations, means forreducing theintensity of the amplified communication currents to thenormal level of audibility,- means-responsive to the voltage of saidpower line to connect the transmitting and the receivingapparatusidirectly with said station connecting line when said powerline is deenergized and to connect the transmitting apparatus with saidstation connecting line through said amplifying means and to connect thereceiving apparatus with said station connecting line throughvthe secondsaid means when said power lineis energized, and means for connectingsaid amplifying means with said power line when said power line isenergized.

9. In a communication system, a power line extending adjacent thesystem, a plurality of stations each having transmitting and receivingapparatus therein, an electrically conductive line connecting saidstations and subject to interference from said power line, means in eachof said stations and energized from said power line for amplifying thecommunication currents originating'within said stations, means forreducing the intensity of the amplified communication currents to thenormal level of audibility, means responsive to the voltage of saidpower line to connect the transmitting and the receiving apparatus insaid stations directly with said station connecting line when said powerline is deene'rgized and to connect the transmitting apparatus with saidstation connecting line through said amplifying means and to connect thereceiving apparatus with said station connecting line through the secondsaid means when said power line is energized, and a switch controllingthe receiving apparatus in said stations whereby the last two said meansare controlled.

DIDIER J OURNEAUX.

